NVIDIA's new 7900GT is expected to use new Samsung GDDR3 memory that's reported to be operating at 1.4ns but frequencies are unconfirmed at this point. In contrast, ATI's X1800XT uses GDDR3 memory with a 1.2ns time running at 1400MHz. NVIDIA's 7800GTX 512 uses memory running at an effective rate of 1.7GHz.